How to clear Scratch Disks

[PhotoshopGenius]

I'm trying to open a 500MB file and received the following Photoshop message: "Could not complete your request because the scratch disks are full."  I went to Edit/Preferences/Performance and only one drive is listed, i.e. my C:.  The active box is checked and it shows 856MB under Free Space.  I read somewhere to uncheck that box to purge/clear the scratch disk, but it wouldn't let me de-select the check box. 

I wasn't able to find technical support on Adobe's site; hopefully someone can help with this.  Thanks!

[SJRiegel]

If photoshop is open, go to the Edit menu and choose Purge > All

[Test Screen Name]

After that, well, it's your disk, full of your files. Only you can decide what to delete, or decide to but more disk.

[Peru Bob]

Please don't ask the same question on two different threads.

Please see here to continue discussion:

How to clear scratch disks for Photoshop CS 6???

I am locking this thread.